In the current Internet system, an Internet Service Provider (ISP) provides Internet connections to customers or subscribers. The ISP is connected to other ISPs by backbones which are generally operated by other companies. In order to connect to the Internet, the ISP will buy bandwidth on one of the Internet backbones which distributes data between various ones of the ISPs and also between data sources. An ISP in Singapore will, for example, buy bandwidth on trans-pacific cables between Singapore and the United States and on cables between Europe and Australia and Singapore. The bandwidth purchased is symmetric. However, many ISPs in the Asia-Pacific Region for example, are net downloaders of bandwidth as the end users of the digital data—i.e. customers of an ISP from those regions—are more active “consumers” of data produced outside of their region than they are providers of data to the Internet. It is also possible for an ISP to also be stakeholder in a backbone system.
Thus the ISP in the Asia-Pacific region is a net downloader of data from the Internet. However, the ISP has purchased symmetric capacity on the Internet backbones. The capacity purchased is sufficient to accommodate the required download rates for data requested by the ISP customers. However, there is substantial overcapacity for uploading data from the ISP to the Internet. As a result, uploading of data from the Asia-Pacific ISP to the rest of the Internet will require little additional costs. Much of the hardware, such as switches, is symmetric and therefore to upload data to the network there would be little increase in installed costs.
A Content Delivery Network (CDN) is a system of computers networked together across the Internet that cooperate to deliver digital data in the form of content (such as large media content including videos and audio files) to end users. Examples of such content based CDN's include Sandpiper and Skycache as well as Akamai and Digital Island and the Applicant's own VelociX network. The Akamai CDN, for example, supplies many connections to many users from a single source.
The CDN has one or more servers on which content is stored. These CDN servers are generally deployed in multiple locations and can often be reached from an ISP over multiple backbones. These CDN servers will cooperate with each other to satisfy requests for content by end users, such as the ISP customers. In prior art systems, the CDN servers will move content behind the scenes to optimize the delivery process of the digital data to the end user. The optimization of the delivery process can take the form of reducing bandwidth costs and/or improving end-user performance.
The number of CDN servers in the CDN varies and depends on the architecture of the CDN. Some of the CDN's have thousands of nodes with tens of thousands of servers. When a user wishes to download content, generally requests for content (digital data) are sent to the CDN from an end user. These content requests are directed to the one of the CDN servers which can provide the best service. When optimizing for service, the CDN servers located in the geographical locations that can serve the requested content most quickly to the end user will generally be chosen to serve the content request. This choice of CDN server may be governed by the principle of choosing the geographical locations that are the fewest hops or fewest number of network seconds away from the end user requesting the digital data (termed the requestor). Alternatively the CDN known in the prior art will chose the CDN server so as to optimize the delivery of the digital data across local networks. When optimizing for cost, CDN servers located in the geographical locations that are less expensive to serve from may be chosen to serve the content request. Often these two goals tend to align, as those CDN servers that are close to the end user have in the prior art systems an advantage in serving costs because they are located within the same network as the end user.
Co-Pending UK Patent Application No GB061596.3 (& U.S. patent application Ser. No. 11/598,115) discloses a content distribution network in which a data monitoring device at a server monitors at least one quality of service (QoS) parameter for the delivery of digital data. The patent application discloses that one of the QoS parameters may be the cost of delivery of the digital data.
Co-Pending UK Patent Application NO GB0615962.8 [(& U.S. patent application Ser. No. 11/598,114) assigned to CacheLogic Ltd, Cambridge, UK teaches a content distribution network in which the selection of the cache from which to download the digital data is obtained is based, at least in part, on the location of the user selecting the digital data.
U.S. patent application No US 2004/0148344 assigned to Serenade Systems, Mountain View, Calif., USA, shows a content distribution network using the Internet. The Serenade system shows a peer-to-peer network in which peer groups are associated and maintained for efficient file distribution. Caches in this application are prioritised based on availability and cost. The network may be configured such that any peer which is not exploiting its available or maximum desired serving bandwidth begins pushing out content to the peer-to-peer network. As mentioned above, CacheLogic Ltd, Cambridge, UK currently offers a VelociX video delivery system which allows a client wishing to deliver digital data, such as a video, to do so at an assigned delivery speed and/or at a fixed cost. This allows, for example, end users paying a premium price for the receipt of the video to receive it within a guaranteed timeframe, rather than waiting for the arrival of the complete digital data to be dependent on network conditions. The VelociX video delivery system is disclosed at http://www.cachelogic.com/home/pages/video/index.php [downloaded 16 Jun. 2007]
Efforts in the past for creating a market-based resource allocation system for the provision of network bandwidth capacity for the distribution of digital data are known. For example, international patent application No WO 01/88811 assigned to Invisible Hand Networks teaches the creation of a spot-market system for the purchase of bandwidth and/or buffer space.